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B. GRAY & P. L. POPE.

SIGNALING APPARATUS FOR TELEPHONE AND TELEGRAPH LINES.

Patented Aug. 28,1883.

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' E. GRAY & F. -L. POPE.

SIGNALING APPARATUS FOR TELEPHONE AND TELEGRAPH LINES. No. 284,003. Patented Aug. 28, 1883.

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5 Sheets-Sheet 4. E'. GRAY & IE. L. POPE.

SIGNALING APPARATUS FOR. TELEPHONE AND TELEGRAPH LINES. No. 284,003.

Patented Aug. 28, 1883.

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SIGNALING APPARATUS FOR TELEPHONE AND TELEGRAPH LINES.

N0. 284,003. Patented Aug. 28, 1888. A 29.10,

1r 1 WITNESSES INVENTORS' Elisha Gr w w (2/ By their flltorneys Fran]: Li Zn.

It FETERS. PfloloJ-ilhognphcr. Wuhmglon. D. C.

ELISIIA GRAY, OF HIGHLAND rrrcnt PARK, ILLINOIS, AND FRANK L. POPE, OF

ELIZABETH, NE\V JERSEY,

SIGNALING APPARATUS FOR TELEPHONE AND TELEGRAPH LINES.

T0 00% whom it may concern:

Be it known we, ELISIIA GRAY and FRANK L. Porn, citizens of the United States, residing, respectively, at Highland Park, in the county of Lake and State of Illinois, and at Elizabeth, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Signaling Apparatus for Telephone and Telegraph Lines, of which the following is a specification.

Our invention relates to an improved meth- 0d of and apparatus for signaling upon telegraph or telephone lines, to be used in cases in which it is desirable or necessary to place a number of different stations upon the same line or circuit.

The special object of the invention is to en able the operator at the central or principal station of such line to sound a call or alarm at any one of the sub-stations thereupon and not at the others, and, conversely, to enable a person at either one of said sub-stations to transmit an alarm or signal to the central station without actuating the apparatus at any of the other substations.

The subject-matter claimed as new will be specifically designated in the claims at the end of this specification.

In the accompanying drawings, Figure 1 is a plan view of the apparatus at the central office as constructed and adapted for signaling 7 at pleasureto either one of three substations upon the same line. Fig. 2 is an inverted plan, and Figs. 3 and 4 are vertical sections, of a portion of said apparatus. Fig. 5 is a front elevation of the complete signaling and alarm apparatus at one of the sub-stations. Fig. 6 is a side elevation ofa portion of the same. Figs. 7, 8, and 9 are detached sectional views of a portion of said apparatus; and Fig." 10 is a theoretical diagram, illustrating the connec tions. of the central office with three sub-stations;

Referring to Fig. 1, A is a base-board, upon which are placed three transmitters, B, B and B", together with three keys, G, 0 and O, by means of which the said transmitters may be respectively brought into action, as

hereinafter explained. D is an electromagnetic call or alarm bell of the ordinary con- August 28,1883. I

struction, by means of which audible signals are received from the different sub-stations upon the line. Each of the transmitters B, B and B consists, substantially, of a steel reed, the several reeds being tuned to determinate and different musical pitches or rates of vibration. Each transmitter-reed has a circuitbreaking contact-spring mounted upon or attached to it; hence it will be understood that when an electric circuit is made to include the circuitbreaker attached to anygiven reed the said circuit will be alternately broken and closed at a definite and predetermined rate per unit of time, which rate of interruption will be invariable in the case of any given reed, and will depend upon the construction or ad justment of the reed itself. In order to maintain the reeds of the several transmitters in vibration, we prefer to make use, in connection with each reed, of an electromagnetic apparatus, as shown in the drawings, Figs. 1 and 10, similar to that set forth and described in Letters Patent of the United States No. 165,728, granted to Elisha Gray on the 20th of July, 1875, to which reference is had.

It will be sufficient in the present connection to state that each reed, as 1), Figs. 1 and 10, is maintained incontinuous vibration at 7 its normal rate by the alternate attraction of two electromagnets, E and c, which face each other on opposite sides thereof and act upon it as upon a common armature. These electro-magnets are alternately brought into action by means of a contact-spring, I), mounted upon the reed I), which plays against an ad justable contactstop, 6 and alternately makes and breaks the circuit of a local battery, F. (See Fig. 10.) The reed of each transmitter is thus kept in continuous vibration, preferably by means of a local battery. Each of the transmitters'B, B, and B, is placed in a separate branch of the main circuit, which latter extends to the sub-stations, and the several branches are closed by their respective keys G, 0 and 0" when it is desired to transmit their vibrations over the line.

' A constant current is maintained upon the main line L by means of a main battery, G, at the central oflice. WVhen the apparatus is at rest, the circuit may be traced as follows: from the earth at the central office by the wiresw and v w to the contact-point o, thence by the contactsprings s to the contact-stop o", thence by the contact-spring 8 wires w" w and contactstop w to the contact-spring m, and thence by the wire 20 to the positive pole of the main battery G; thence from the negative pole of said "battery by the wire 10 to the. contactspring thence by contact-stop w" and wires w w to the electro-magnet of the signal-bell D, and thence to the line L, which extends to and through the several sub-stations designated as stations 1, 2, and 3, and finally to the earth at the terminal station.

Upon an insulating-support, T, Figs. 2, 3, 4, and 10, is mounted a series of metallic springs, 15, t and t the free ends of which project over and are situated just above the free ends of a series of contact-springs, s s 8 while upon the former series of springs are mounted knobs or finger-keys 0, O and G The contact-sprin gs a; wjare also mounted upon the insulating-supportT', their free ends being united by a non-conducting bar, X, which passes directly underneath the free ends of the springs 8, s and 8 The key-springs t t t" are connected by wires 3 y y with the re spective reeds of the transmitters B B B after which they are united to a common wire, .2, which is connected directlywith the earth.

The apparatus at each of the sub-stations 1,

" 2, and 3 is constructed in precisely the same manner. It will therefore be sufficient to describe the apparatus at one station-for example, station 2.

-Beferring'to Fig. 5, I is a box or case Within which the apparatus is placed. The front of the box is ordinarily closed by a suitable door, z',which in the drawings is represented as being thrown open in order to exhibit the apparatus within. This apparatus consists of an ordinary self-interrupting call or alarm bell, J, actuated to a suitable standard, 0, whileits normal rate of vibration may be adjusted within certain limits by means of a movable weight, 0, capableof being clamped at any point along its length by means of a screw, 0. A polarized or permanently-magnetic armature-bar, P, is pivoted at p in such a position that one of its polar extremities is situated directly between the polar extensions m m of the electro-inagnet M, while its opposite extremity oscillates between two adjustable stops, q 1 the former of which is an electrical contact stop, while the latter is insulated. These stops are adjusted in such a manner as to permit the polarized bar P to oscillate to and fro upon its axis 19 between the poles m m of the electro-magnet M, but not to come in actual contact with either of them; hence the magnetic attraction between the end of the polarized bar P and the soft-iron polar extensions of the electro-magnet M will tend to retain the former in its position at either extremity of its vibration when no current is traversing the electro-magnet M.

R is a metallic bar pivoted loosely to an upright standard, R, with one of its extremities normally resting upon and in electrical contact with the free end of the reed O. The electromagnet M and circuit-breaking key H are included in the main-line circuit L, While the electro-magnet K, which actuates the station call or alarm bell J, is included in an independent local circuit. The electrical connections will be best understood by referring to Fig.

10, (see station 2.) The line-wire Lfirst passes through the circuit-breaking key H, thence through the electro-magnet M, and thence to the next station in the series.

Q is a local battery, one pole of which is connected by a wire, q, with one terminal of the coil of the electro-magnet K of the callbell J. The other terminal of the electromagnet is connected by a wire, q, with the self-interrupting contact 76, from which a wire, 1 extends to andis connected with the polarized bar or armature l The contact-stop g is connected by a wire, q, with the other pole of the local battery Q. The

7 wires (1 and (f of the local circuit are normallyunited by a shunt, (1 which traverses the reed O and the pivoted bar It, and thus diverts the local circuit from the electromagnet K when the polarized armature P is in contact with the stop q, except as hereinafter stated. The polarity of the armature Pis such that when the constant current from the battery G at the central office traverses the main line L the attraction of the electro-magnet M will tend to hold the bar P against the insulated stop q, and thus keep the local circuits interrupted at all the substations.

The reed-armature O at each sub-station is adjusted by means of its sliding weight 0, or

otherwise, in such manner as to have the same normal rate of vibration as its corresponding transmitter at the central office, and hence when any particular transmitting-reed is set in action the particular receiving-reed which is adjusted in harmony with it will respond, while the others in the series will remain wholly unaffected.

The operation of the apparatus is as follows: When the main line is in its normal position of rest and ready for use, it is traversed by a constant current from the negative pole of the main battery G at the central station, as hereinbefore explained. This current passes through the .keys H and the electroecmcea a magnetsM ateach sub-station, and the polarity of the magnetism generated thereby defieets the polarized armature P at each sub-station, keeping it in contact with the insulated stop In case the operator at any sub-stati on desires to transmit a call or signal to the central station, he does so by depressing his key and breaking the main circuit. This causes the bell l) at the central station to be struck by the release of its actuatingarmature, but

' no effect will be produced upon the apparatus V only thereto.

at any of the other substations in the circuit. If, on the other hand, the operator at the cen tral oifice wishes to transmit a call signal to one of the sub-stationsfor example, station 2 he depresses the key 0 which may conveniently be marked with a number corresponding to the number of the station. The depression of the key 0 establishes a connection between the spring t and the spring 8 and at the same time breaks the contact previously existing between the spring 5* and the stop o". By the same operation the bar X is depressed and the springs 00 w are respectively removed from contact with the terminals 10 and w" of the wires 20 and w, and brought into contact with the wires w and w. This operation produces the twofold effect of switch ing the main-line circuit through the appropriate vibrating transmitter-reed B and of reversing the polarity of the main battery G with respect to the line. The change of the polarity of the mainline current causes the polarized armature l at every one of the substations to be deflected from its normal position, thus bringing it in contact with the stop qtand closing the circuit of the local battery Q. The closing of the local battery in this manner will, however, in itself produce no effect upon the electro-magnet K of the alarm- .bell, as the latter is shunted by the contact between the reed O and the vibrating bar 1%, which rests upon it. The reed O at station 2 being adjusted to vibrate in response to the reed of the transmitter B ,will be set in vibration, and this vibration will cause the looselypivoted bar R to hop up and down, interrupt the shunt-circuit, and allow the magnet K to become active, thus causing the bell J to ring. The bells at all the other substations, being cut out by the action of their respective shunts, will remain quiescent. The bells of all the stations are actuated in precisely the same manner, the only difference being that the reed-armature O in each instance is adjusted to vibrate in harmony with its corresponding transmitter at the central office and to respond By increasing the number of transmitters and tuning them to different rates of vibration, a very large number of in dependent sub-stations may be signaled from a central station 011 one line without interference with each other. Asingle series of trans mitting-reeds at the central office may be arranged in such a manner as to be capable of being shifted from one to another of several different lines radiating therefrom, each of which may have a series of sub-stations provided with apparatus tuned to correspond with the several transmitters, thereby avoiding the expense and complication of a separate set of transmitters for each line.

Vie are aware that it is not new to employ a freely-susp ended pendulum at atransmittingstation for sending electric impulses through a circuit at regular intervals, nor to cause rhythmical impulses thus transmitted to act upon another suspended pendulum of corresponding length, and thus gradually to cause the same to oscillate in an arc of sufficient amplitude to strike a bell. Our invention differs essentially from this well-known device, inasmuch as we employ a resilient vibrating reed, and not a pendulum. Such a reed possesses the important practical advantage of being instantaneously set in action when such rhythmical current is made to act upon it, while a pendulum requires considerable time before it can be brought into vibration to strike the bell, while the first stroke so made will throw the pendulum out of beat and prevent the repetition of the alarm.

We hereby disclaim, so far as this specification and these Letters Patent are concerned, all inventions shown, described, and claimed, or to be claimed in our original application, filed December 15, 1881, serial number 47,964, of which this application is a division. This disclaimer is intended to embrace, and does embrace, .every invention not specifically claimed in the several claims at the end of this specification, and all inventions shown, described, or otherwise set forth herein, and which are also found in said original application, but not claimed herein, are left in said original application.

We claim as our joint invention- 1. The combination, substantially as hereinbefore set forth, of a main battery, a normallyclosed main circuit, a transmitter at the central station, having a determinate rate of vibration, a key for connecting said transmitter with the main line, an electro-magnet at a substation, a vibrating reed-armature actuated by said electro-magnet and adjusted to respond only to the vibrations of its corresponding transmitter, and an audible signal or alarm controlled by said armature.

2. The combination, substantially as h ereinbefore set forth, of a main battery, a normallyclosed main circuit, a pole-changing device, a transmitter adjusted to a definite rate of vibration, an electromagnet, a polarized armature, and a reed-armature, both actuated by said electro-magnet, and an audible signal or alarm controlled by the joint action of the polarized and reed armatures.

3. The combination, substantially as herein before set forth, of a main battery, a nor1nallyclosed main circuit, an electromagnetic signal-bell at the central office included in said main circuit, a key at a sub-station for inter- IIO rupting said main circuit, a transmitter at the central station, adjusted to a determinate rate of vibration, a key at the central station, for placing said transmitter in connection with the main line, an electro-magnet at the submined rate of vibration for interrupting the said shunt.

5; The combination of a main battery, a normally-closed main circuit, a series of transmitters adjusted to determinate and different rates of vibration, a series of keys whereby any one of said transmitters may be placed in connection with the main circuit, a series of 25 electro-magnets at different receiving-stations,

a series of reed-armatures actuated by said electro-magnets and adjusted to determined and different rates of vibration corresponding with those of the respective transmitters, and 0 a series of call or alarm bells, each ,of which is actuated by the vibration of its corresponding reed-armature.

In testimony whereof we have hereunto subscribed our names, the said ELISHA GRAY, on 3 5 the 12th day of July, A. D. 1883, and the said FRANK L. POPE, on the 23d day of July, A.

ELISHA GRAY. FRANK L. POPE. V \Vitnesses to signature of Elisha Gray:

S; M. MILLARD, O. F. MoREY. Witnesses to signature of Frank L. Pope:

DANIEL W. EDGEOOMB, CHARLES A. TERRY. 

